1. Field of the invention
The present invention relates to a radiation imaging detection technology, in particular to a micro dose radiation inspection apparatus for object security inspection, which allows all of rays transmitting through an inspected human body to be collected effectively and be used for imaging.
2. Description of the Related Art
In recent years, as criminal activities, such as by the international terrorist organization, are increasingly rampant, requirements to modern security guaranteeing apparatuses are enhanced. They are required to inspect areas on skins of persons and within bodies of persons. Furthermore, the security guaranteeing apparatuses may be classed into metal and non-metal security inspection apparatuses according to inspection type.
Current metal detectors used widely for inspecting bodies of persons can only find the presence of metals, but they fail to determine the positions and shapes of the metal objects on the bodies. For some dangerous goods, such as plastic explosives and weapons, although they may be inspected and detected, to some extent, by various electronic noses, the electronic noses cannot do anything to plastic weapons and tightly packed bombs. Thus, such dangerous goods typically will be inspected and recognized only by contacting them by inspectors. However, this approach has a low efficiency and causes a significant inconvenience and slight irreverence to all of participants.
In recent years, with development of ion migration spectra (IMS) technology, it becomes possible to detect suspicious particles, such as drugs and explosives, carried by human bodies. For example, an IMS gate type inspection technology may be used, to some extent, to inspect and detect dangerous goods and drugs carried around bodies of persons, but it still fails to inspect dangerous goods and drugs carried within bodies of persons.
At present, only radiation imaging technology, for example, X-ray radiation imaging technology, may meet all of the above requirements for inspection. The basic principle of X-ray radiation imaging technology is that different substances have different absorptive ratios to X-ray emitted from an X-ray source when the X-ray transmits through the bodies of persons to be inspected; and the X-rays which are not absorbed can be converted into electrical signals with various intensities after being collected by detectors, and the electrical signals can be converted into digital signals for display of images by being sampled and processed.
In some of the conventional X-ray radiation imaging body security inspection systems, after transmitting through bodies of persons, the X-rays emitted from the ray source, such as X-ray machine, are collimated and then form a radiation area on a detector, the radiation area including an effective detection area of the detector. Thereby, the part of the X-rays emitted from the ray source and irradiated on the effective detection area of the detector may be sampled and processed, while the part of X-rays which are not irradiated on the detector will not be detected effectively.
Since a considerable part of the X-rays cannot be detected effectively, an absorptive dose for a single inspection has to be enhanced in order to obtain imaging results with same accuracy or sharpness when the bodies are detected in practice. Obviously, it may damage public radiation security. However, if an absorptive dose for a single inspection is reduced, the resulting accuracy or sharpness of the radiation imaging will be reduced inevitably.
Furthermore, in the existing X-ray radiation imaging body security detection processing, the persons to be inspected have to move, while the radiation generator and the detector are kept stationary. In this case, movement of the persons to be inspected may cause a pseudo-image in the collected images, which will seriously degrade qualities of images, including sharpness.